Relationships between the functional plasticity of cortical representations and the acquisition and retention of new motor skills in the primary motor cortex of adult primates will be examined using modern neurophysiological and behavioral training techniques. Specifically, the respective roles of increased motor use and increased motor skill on the alterability of sensory and motor representational maps in area 4 will be assessed by comparing pre-training representations with post-training representations. In addition, the role of different classes of sensory input to area 4 on motor topography and alterability will be examined by evaluating differences between rostral and caudal subregions of primary motor cortex. This research will help clarify the neural mechanisms responsible for the vast array of manual abilities and capacity for motor learning exhibited by higher animals. From a clinical perspective, an understanding of the motor cortex has the potential for providing a model for examining the neurophysiological bases of recovery of motor function following brain damage.